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R Daniels

Publications and source records attributed to R Daniels.

At least 19 recordsLinked to original sources
PubMed2006

Scientific lessons from the first influenza pandemic of the 20th century.

Re-analysis of the influenza pandemic of 1918 has given reassurance about a rather low reproductive number (R(o)), a prolonged herald wave of virus and that the skewed mortality towards the young adult could be a singularly unique event dependent upon previous infection history, perhaps not to be repeated in a future pandemic. Over 99% of those who contracted the virus survived, in spite of the absence of antivirals, vaccine and antibiotics for the secondary bacteria infections which probably accounted for one-third of the 50 million deaths. Therefore, in spite of a three-fold population increase since 1918 and 100 thousand plane journeys daily, judicious and careful planning together with a stockpile of antiviral drugs, oseltamivir, zanamivir and M2 blockers and a generic H5N1 vaccine, and application of hygiene would be expected to reduce mortality in a new pandemic, to figures significantly less than 1918.

Disease Outbreaks↗
PubMed2005

A hypothesis: the conjunction of soldiers, gas, pigs, ducks, geese and horses in northern France during the Great War provided the conditions for the emergence of the "Spanish" influenza pandemic of 1918-1919.

The Great Influenza Pandemic of 1918-1919 was a cataclysmic outbreak of infection wherein over 50 million people died worldwide within 18 months. The question of the origin is important because most influenza surveillance at present is focussed on S.E. Asia. Two later pandemic viruses in 1957 and 1968 arose in this region. However we present evidence that early outbreaks of a new disease with rapid onset and spreadability, high mortality in young soldiers in the British base camp at Etaples in Northern France in the winter of 1917 is, at least to date, the most likely focus of origin of the pandemic. Pathologists working at Etaples and Aldershot barracks later agreed that these early outbreaks in army camps were the same disease as the infection wave of influenza in 1918. The Etaples camp had the necessary mixture of factors for emergence of pandemic influenza including overcrowding (with 100,000 soldiers daily changing), live pigs, and nearby live geese, duck and chicken markets, horses and an additional factor 24 gases (some of them mutagenic) used in large 100 ton quantities to contaminate soldiers and the landscape. The final trigger for the ensuing pandemic was the return of millions of soldiers to their homelands around the entire world in the autumn of 1918.

Animals↗
PubMed2004

Trace metal speciation and contamination in an intertidal estuary.

An analysis of the geochemical distribution of selected trace metals among various geochemical phases of the sediments in the Tees estuary was carried out using a sequential extraction technique and Differential Stripping Voltammetry. The sediments of the estuary are mainly organic rich clay silts and metal concentrations exceed those in the water column. Speciation results show that contamination of the estuary is mainly from anthropogenic sources. Pb and Zn are associated with the reducible, residual and oxidisable fractions. The speciation pattern of Cd was similar to those of lead and zinc. However there were also some exchangeable and bound to carbonate fractions although these were less significant. Cu is largely associated with the oxidisable and residual fractions, with insignificant bound to carbonate, exchangeable and reducible fractions. The most bioavailable forms of the metals are the free inorganic ions. Total metal concentrations in the estuary display a downward trend since the 1970s.

Adsorption↗
PubMed2004

Peptide signal molecules and bacteriocins in Gram-negative bacteria: a genome-wide in silico screening for peptides containing a double-glycine leader sequence and their cognate transporters.

Quorum sensing (QS) in Gram-negative bacteria is generally assumed to be mediated by N-acyl-homoserine lactone molecules while Gram-positive bacteria make use of signaling peptides. We analyzed the occurrence in Gram-negative bacteria of peptides and transporters that are involved in quorum sensing in Gram-positive bacteria. Many class II bacteriocins and inducing factors produced by lactic acid bacteria (LAB) and competence stimulating peptides (CSPs) synthesized by streptococci are processed by their cognate ABC-transporters during their secretion. During transport, a conserved leader sequence, termed the double-glycine motif (GG-motif), is cleaved off by the N-terminal domain of the transporter, which belongs to the Peptidase C39 protein family. Several peptides containing a GG-motif were recently described in Gram-negative bacteria (Trends Microbiol 2001;9:164-8). To screen for additional putative GG-motif containing peptides, an in silico strategy based on MEME, HMMER2.2 and Wise2 was designed. Using a curated training set, a motif model of the leader peptide was built and used to screen over 120 fully sequenced bacterial genomes. The screening methodology was applied at the nucleotide level as probably many small peptide genes have not been annotated and may be absent from the non-redundant databases. It was found that 33% of the screened genomes of Gram-negative bacteria contained one or more transporters carrying a Peptidase C39 domain, compared to 44% of the genomes of Gram-positive bacteria. The transporters can be subdivided into four classes on the basis of their domain organization. Genes coding for putative peptides containing 23-142 amino acids and a GG-motif were found in close association with genes coding for Peptidase C39 domain containing proteins. These peptides show structural similarity to bacteriocins and peptide pheromones of Gram-positive bacteria. The possibility of signal transduction based on peptide signaling in Gram-negative bacteria is discussed.

Amino Acid Motifs↗
PubMed2001

Comparison of gene transcription in cloned bovine embryos produced by different nuclear transfer techniques.

The efficiency of animal production using cloning technology is still relatively low and research to determine a more efficient nuclear transfer procedure is ongoing. One approach which may be informative in assessing the viability of nuclear transfer embryos is the analysis of embryonic gene expression. Using RT-PCR techniques we have previously detected the aberrant expression of FGF4, FGFr2 and IL6 in a significant proportion of bovine granulosa cell-derived nuclear transfer embryos, which correlated with a limited developmental potential in vivo. In order to analyse the effect of different donor cell nuclei on embryonic gene expression we have now analysed the expression of these genes in nuclear transfer embryos reconstructed with fetal epithelial cell nuclei. In addition, we have compared the expression of these genes in bovine nuclear transfer embryos produced by cell fusion or direct injection with variations in the timing of oocyte activation. In all nuclear transfer embryos analysed, FGFr2 and IL6 transcripts were detected at a similar rate to that in IVF embryos. However, the absence of FGF4 transcripts was again evident in a large proportion of nuclear transfer embryos and most significantly in those embryos whose development was activated almost immediately following the transfer of the donor nucleus. The results demonstrate the effects that different donor cell lines and different nuclear transfer procedures may have on the expression of developmentally important genes in nuclear transfer embryos.

Animals↗
PubMed2001

Treatment of grade 4 renal stab wounds with absorbable fibrin adhesive bandage in a porcine model.

PURPOSE: In a porcine model we evaluated the efficacy of the absorbable fibrin adhesive bandage and other novel fibrin products for treating major renal stab wounds. MATERIALS AND METHODS: In commercial swine we produced an almost lethal, grade 4 renal stab wound via a 3.5 cm. sagittal, centrally located, through-and-through laceration. Each pig then received treatment in random fashion, including conventional oversewing of capsular defects with absorbable gelatin sponge and horizontal mattress sutures in 6, external absorbable fibrin adhesive bandage that was pressure held for 60 seconds in 6, external and internal absorbable fibrin adhesive bandage that was applied externally, inserted into the renal defect and pressure held for 60 seconds in 6, liquid fibrin sealant that was placed in the laceration and held for 60 seconds in 8, fibrin foam that was applied in the same manner as liquid fibrin in 5 and closing of the peritoneum over the lacerated kidney without further treatment in 6. Blood loss and time to hemostasis were recorded. Animals were sacrificed at 6 weeks to evaluate the injured renal unit. RESULTS: Compared with conventional therapy the absorbable fibrin adhesive bandage applied externally alone or externally and internally resulted in significantly less bleeding and significantly less time to hemostasis (p <0.001). Liquid fibrin and fibrin foam did not reliably achieve hemostasis. Postoperatively computerized tomography and histological sectioning suggested that the absorbable fibrin adhesive bandage results in a stable, durable clot and healing is at least as successful as with conventional treatment. CONCLUSIONS: The absorbable fibrin adhesive bandage appears to be a safe, rapid means of renal salvage after injury.

Animals↗
PubMed2001

The Medical Education Commission report on trends in graduate medical education 2001.

The state of Louisiana Medical Education Commission offers the second publication in the Journal of Louisiana State Medical Society on Graduate Medical Education (GME) in Louisiana. The four previous annual reports of the Commission have provided data to focus on trends in size, status, proportions, and issues on GME. The Commission was established by Act 3 of the 1997 Louisiana Legislature. This summary report for 2001 provides the detailed and updated data on all GME residents and fellows in Louisiana for the last academic year. The presentation of data and trends poses three questions for analysis. First, what are the trends in Graduate Medical Education in Louisiana for total residents and fellows? Second, how do these trends relate to the size, status, and proportions of Graduate Medical Education in Louisiana and as compared to the United States? Third, where do these trends lead to the future in predictions and recommendations for Graduate Medical Education in Louisiana? The 4-year trend in the total number of Graduate Medical Education filled positions has been relatively consistent, with some recent increases in primary care residency positions, especially in Family Medicine and Medicine/Pediatrics. These increases will plateau as current trends on new program formation stabilize, requiring emphasis on recruitment and factors promoting recruitment for GME in the state of Louisiana. The state of Louisiana has participated proportionately relative to population in the growth of medical education in the last century and compares favorably with other states and the nation. Louisiana has exceeded national averages in the increases in primary care programs and residents and in the retention of trainees in practice sites in the state.

Education, Medical, Graduate↗
PubMed2001

Gene expression studies on human primordial germ cells and preimplantation embryos.

Research on the regulation of gene expression in human germ cells and preimplantation embryos is restricted due to the scarcity of samples and the requirement for highly sensitive molecular techniques to investigate the few cells available. To overcome these difficulties, we have developed a reliable procedure capable of generating amplified cDNA preparations from single cells. Using this procedure, we prepared cDNA from primordial germ cells (PGCs) isolated from the gonads of fetuses at 10 weeks gestation and from preimplantation embryos at the 1-cell, 4-cell, 8-cell and blastocyst stages. Our cDNA preparations allow us to investigate the expression profile of an almost unlimited number of different genes in the same sample preparation. This is of great advantage for studies of a panel of genes in a particular family or functional group, or with related mechanisms of regulation, e.g., developmental genes, oncogenes, cell cycle-control genes and imprinted genes. We have used these cDNA preparations in conjunction with differential display to identify genes specifically expressed in PGCs and preimplantation embryos in a sex- and developmental stage-specific manner. Genes specifically expressed in PGCs, oocytes and embryos were further analysed for their expression in embryonal carcinoma cells and in their differentiated derivatives following treatment by retinoic acid. Our strategy will disclose genes essential for gametogenesis and embryonic development which may only be expressed at certain stages of their development. The germ cell- and embryo-specific cDNA molecules, cDNA libraries and microarrays are a valuable resource for other researchers in this field.

Blastocyst↗
PubMed2000

Localization, expression and genomic structure of the gene encoding the human serine protease testisin.

Testisin is a recently identified human serine protease expressed by premeiotic testicular germ cells and is a candidate tumor suppressor for testicular cancer. Here, we report the characterization of the gene encoding testisin, designated PRSS21, and its localization on the short arm of human chromosome 16 (16p13.3) between the microsatellite marker D16S246 and the radiation hybrid breakpoint CY23HA. We have further refined the localization to cosmid 406D6 in this interval and have established that the gene is approximately 4. 5 kb in length, and contains six exons and five intervening introns. The structure of PRSS21 is very similar to the human prostasin gene (PRSS8) which maps nearby on 16p11.2, suggesting that these genes may have evolved through gene duplication. Sequence analysis showed that the two known isoforms of testisin are generated by alternative pre-mRNA splicing. A major transcription initiation site was identified 97 nucleotides upstream of the testisin translation start and conforms to a consensus initiator element. The region surrounding the transcription initiation site lacks a TATA consensus sequence, but contains a CCAAT sequence and includes a CpG island. The 5'-flanking region contains several consensus response elements including Sp1, AP1 and several testis-specific elements. Analysis of testisin gene expression in tumor cell lines shows that testisin is not expressed in testicular tumor cells but is aberrantly expressed in some tumor cell lines of non-testis origin. These data provide the basis for identifying potential genetic alterations of PRSS21 that may underlie both testicular abnormalities and tumorigenesis.

Alternative Splicing↗
PubMed2000

Hydroxypropylmethylcellulose (HPMC) as emulsifier for submicron emulsions: influence of molecular weight and substitution type on the droplet size after high-pressure homogenization.

Hydroxypropylmethylcellulose (HPMC) is a known emulsifier as well as a common viscosity enhancer in eye drops. Therefore, HPMC stabilized emulsions appear as interesting drug carriers for ophthalmic use and as a suitable treatment of dry eye syndrome. Since submicron emulsions are known to have an improved drug delivery, attempts were made to reduce the emulsion's droplet size by high-pressure homogenization. Droplet size was dependent on the homogenization pressure and the polymer content. Differences were found between emulsions stabilized with higher and lower molecular weight HPMC. Smaller droplet sizes were obtained with the shorter chained HPMC. No considerable influence of the substitution type was observed.

Drug Compounding↗
PubMed2000

Movement of petroleum hydrocarbons in sandy coastal soils.

In a field trial, oiled beach sand was buried in a coastal dune system in south Wales. A monitoring programme was designed to assess the rate of leaching of inorganic ions and hydrocarbons from the deposit. Active breakdown of the weathered oil occurred within the oiled beach sand, but hydrocarbons from the original material, or arising as a result of degradation, did not follow the same leaching pattern as inorganic ions; they remained within the original deposit. The results suggest that weathered oil coming ashore from spills at sea can be mixed with sand and buried to degrade in coastal soils, without risk of groundwater contamination by hydrocarbons.

Environmental Monitoring↗
PubMed2000

Partial "repair" of defective NEF genes in a long-term nonprogressor with human immunodeficiency virus type 1 infection.

A 36-bp deletion close to the 5' end of NEF that impaired Nef function was found in a long-term nonprogressor with human immunodeficiency virus type 1 (HIV-1) infection. Forms containing an adjacent duplication of 33 bp were also frequently observed. The duplication showed no homology to the deleted region but restored the overall length of the first variable loop of Nef. NEF alleles carrying the duplication were active in class I major histocompatibility complex (MHC-I) down-modulation and enhancement of virus infectivity. However, they showed little activity in CD4 down-regulation and were unable to stimulate viral replication in human peripheral blood mononuclear cells. Our study indicates that the enhancement of virion infectivity and the stimulation of HIV-1 replication in lymphocytes are distinct functions of Nef. Our findings also illustrate the capacity for repair of attenuating deletions in HIV-1 infection and suggest that a selective pressure for Nef-mediated MHC-I down-modulation and/or enhancement of virion infectivity exists.

Adult↗
PubMed2000

Analysis of gene transcription in bovine nuclear transfer embryos reconstructed with granulosa cell nuclei.

The low efficiency of animal production using somatic cell nuclear transfer procedures is considered to be the result of an incomplete reprogramming of the donor somatic cell nucleus, which leads to a lack of, or abnormal expression of developmentally important genes. However, our current understanding of the process of somatic cell nuclear reprogramming and its effect on gene expression is limited. In this study, we compare the transcription patterns of six developmentally important genes, Oct4, IL6, FGF2, FGF4, FGFr2, and gp130 in single in vitro fertilized (IVF) and nuclear transfer embryos reconstructed using granulosa cells for the donor nuclei. Similar patterns of transcription were detected for Oct4, FGF2, and gp130 in IVF and nuclear transfer embryos during the preimplantation stages of development. However, a number of morula- and blastocyst-stage embryos derived from nuclear transfer procedures showed abnormal transcription of IL6, FGF4, and FGFr2. Previous studies have demonstrated that these three genes play an important role in implantation, early postimplantation development, or both in the mouse. Therefore, the aberrant transcription patterns detected in nuclear transfer embryos may lead to a reduction in embryo viability.

Animals↗
PubMed2000

Does the absorbable fibrin adhesive bandage facilitate partial nephrectomy?

PURPOSE: To evaluate the ability of the absorbable fibrin adhesive bandage (AFAB), a prototype product comprising lyophilized fibrinogen and thrombin on a VicrylTM mesh backing, to seal the collecting system and control bleeding after partial nephrectomy. MATERIALS AND METHODS: Growing female pigs (n = 18) underwent left nephrectomy and a 40% (by length) right lower pole partial nephrectomy. One of three treatments was immediately applied: Conventional-closure of the collecting system, ligation of visible segmental vessels, application of SurgicelTM with bolstering sutures to the renal capsule; AFAB-application of up to two 4 x 4-inch AFABs held under pressure for 60 seconds; Placebo-application of a hemostatically inert VicrylTM bandage, visually identical to the AFAB. Blood loss and ischemic and total operative times were recorded, and abdominal computerized tomography (CT) was performed on postoperative day 6. Animals were sacrificed at 6 weeks to evaluate the remaining renal mass histologically. RESULTS: Compared with conventional therapy, use of the AFAB resulted in significantly less bleeding (13 versus 68 ml., p <0.001) and lower operative (7.2 versus 16.3 minutes, p <0.001) and ischemic times (3.4 versus 7.8 minutes, p <0.001). Estimated blood loss in the placebo bandage group was dramatically higher (357 ml., p <0.001). Postoperative CT and histological sectioning suggested that the AFAB produces a stable, durable clot and that healing is at least as successful as with conventional treatment. CONCLUSION: Use of the AFAB facilitated performance of partial nephrectomy by reducing blood loss and ischemic and total operative times. The AFAB appears equivalent to conventional surgery in its ability to seal the collecting system.

Absorbable Implants↗
PubMed2000

A neutralizing antibody Fab-influenza haemagglutinin complex with an unprecedented 2:1 stoichiometry: characterization and crystallization.

The haemagglutinin HA is a trimer of identical subunits and is the more abundant viral surface glycoprotein of the influenza virus. It is the target of antibodies that neutralize viral infectivity. Antibodies that bind to HA with 3:1 and 1:1 stoichiometries have been identified. Here, an antibody whose Fab binds to HA with an unprecedented 2:1 Fab:HA stoichiometry is characterized. The complex has been crystallized and synchrotron data to 3.5 A resolution have been collected. Molecular replacement confirms the stoichiometry of the complex.

Antibodies, Viral↗
PubMed2000

Performance of GC-MS and MOSES II, a hybrid modular sensor system, for the quantitative detection of the evaporation of the insect repellent N,N-diethyl-m-toluamide from two different matrices.

The purpose of this work was to determine the evaporated amount of N,N-diethyl-m-toluamide (DEET), a commonly used insect repellent, from two different matrices medium chain triglycerides (MCT) and Polyethylene glycol 400 (PEG), with GC with mass sensitive detection (GC-MS) and a hybrid modular sensor system (MOSES II). Thus, the binary mixtures are equilibrated at 80 degrees C for 45 min and then an aliquot of this headspace is analyzed by GC-MS and a sensory system consisting of an array of eight metal oxide sensors and eight quartz crystal microbalances. Both analytical methods allow a sensitive detection of even small amounts of DEET in the headspace from binary mixtures with the MCT or PEG, respectively. The two additives are found to be very different concerning their behavior to the vapor phase; i.e., the lipophilic (MCT) delivers an almost constant headspace of DEET, while the hydrophilic matrix PEG releases smaller amounts of DEET, which continuously decrease when a multiple headspace extraction is performed. Furthermore, the results reveal that both analytical methods lead to comparable results with the MCT/DEET mixtures whereas differences were seen with mixtures containing PEG. This can be attributed to the interaction of volatile portions of PEG with the sensors of the MOSES II.

Autoanalysis↗
PubMed2000

The Medical Education Commission report at the turn of then new millennium 2000.

The State of Louisiana Medical Education Commission was formed by Act 3 of the 1997 Louisiana Legislature. The members are appointed by the Louisiana State University Health Sciences Center, Tulane University Medical Center, and Alton Ochsner Medical Foundation and report to and advise the Department of Health and Hospitals (DHH). This summation from the Medical Education Committee is designed to answer three questions. First, how does the State of Louisiana compare nationally in the renewal of physician supply and capability? Second, what are the current status and trends of graduate medical education in Louisiana? Third, what recommendations are proposed to continue and improve the important relationship between the State public hospitals and educational programs? The State of Louisiana has participated proportionately relative to population in the growth and progress of medical education in this last century and compares favorably with other states and the nation. Louisiana exceeds national averages in the increase of primary care residency programs and positions and in the retention of trainees in practice sites in the State. The three-year trends in total number of graduate medical education filled positions has been consistent with only 0.4% change, with primary care showing an overall increase of 9%, reflecting increases in Family Medicine (56%) and Medicine/Pediatrics (41%).

Education, Medical, Graduate↗